The disclosed embodiments concern the field of transport aircraft, such as civilian transport aircraft.
More specifically, the disclosed embodiments concern an aircraft with fixed propulsion engines near the fuselage at a point far from the center of gravity of the aircraft, such as engines installed on the rear of the fuselage.
For reasons of stability and attitude and trajectory control, airplanes generally have tail units combined with aerodynamic control surfaces.
The role of these tail units and control surfaces is well known to aircraft designers, and the dimensions of the tail units, as well as the dynamics of their moving parts, adjustable horizontal plane (trim), elevators or rudders, are determined to meet the requirements for safety, operational performance and comfort.
One widespread aircraft architecture, particularly for civilian transport planes, uses tail units made up of horizontal aerodynamic surfaces, a horizontal tail unit and a vertical aerodynamic surface, a vertical tail unit or fin attached to the fuselage in the rear part in back of the wing, and said surfaces have hinged moving flaps, elevators and yaw control surfaces, respectively, on their trailing edges.
In another known form, the tail units are comprised of two aerodynamic surfaces inclined to form a V, called a V-tail, which simultaneously performs the functions of a vertical and horizontal tail unit.
In these known examples, the propulsion engines are attached to the fuselage or the wing of the aircraft by dedicated means independent of the tail units, and the aerodynamic drag associated with wet shapes and surfaces of the different elements accumulate, as does their weight, which is detrimental to the performance of the aircraft.
In addition, the aerodynamic control surfaces have an effectiveness that varies with the square of the relative speed of the aircraft in relation to the air and, because of the aircraft control conditions at low in-flight and ground speeds, it is generally necessary to use tail units whose dimensions are not justified for cruising, the majority of the time, which is another penalty of the known architectures.
It is also known when an aircraft has laterally distant engines, for example engines under the wing on each side of the axis, how to use different thrusts between the left engine and the right engine to create yawing torque.
However, this type of control, used to manually roll some aircraft, and exceptionally in flight when there is a loss of aerodynamic control, proves limited because of the response time of engines like jets and the impossibility of acting effectively on the pitch axis.